The invention relates to a method and a device for limiting the current in a temperature-dependent manner of an energy storage device for electrical energy.
High voltage batteries, also known as battery packs, are known from the prior art, the high voltage batteries being in mild hybrid, hybrid or electric vehicles and are embodied from multiple individual cells, for example lithium ion cells, that are connected in series and/or in parallel. It is known that the temperature of the cells both during operation as well as while the vehicle is at a standstill influences the serviceable life of the high voltage battery, wherein in particular temperatures that are too high are detrimental to the serviceable life.
So as to limit the aging process caused by the influence of temperature, it is known from the prior art, by way of example DE 10 2007 063 178 A1, DE 10 2007 010 751 A1 or WO 2010/121831 A1, that high voltage batteries of this type are tempered by a cooling system and cooling plates that have fluid flowing through them in order to dissipate any lost heat that occurs so that the temperature of the electrical energy storage device never departs from the permissible operating range.
In addition, it is known from practical use to provide a maximum permissible charging and/or discharging current of the energy storage device so as to limit the thermal loading of the energy storage device, in other words to set an upper limit of the permissible current with which it is possible to charge the energy storage device for the duration of a predetermined time interval or with which it is possible to discharge the energy storage device for the duration of a predetermined time interval, in order not to exceed fixed temperature threshold values. Threshold values of this type can be fixed or set with a view to achieving a desired serviceable life of the energy storage device. However, the disadvantage in this case is that the provision of fixed temperature threshold values of this type for the charging and/or discharging current of the energy storage device is associated with a reduced power capability and flexibility in relation to temporarily fulfilling requirements for high power.